<!DOCTYPE html>
<title>View transitions: event pseudo name</title>
<link rel="help" href="https://drafts.csswg.org/css-view-transitions-1/">
<link rel="author" href="mailto:vmpstr@chromium.org">

<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>

<style>
:root { view-transition-name: none; }
#first {
  background: blue;
  width: 100px;
  height: 100px;
  view-transition-name: shared;
}

html::view-transition-group(*),
html::view-transition-image-pair(*),
html::view-transition-new(*),
html::view-transition-old(*) {
  animation-duration: 600s;
}

@keyframes fade-in {
  from { opacity: 0; }
}
html::view-transition-image-pair(*) {
  animation: fade-in 600s both;
}

</style>
<div id=first></div>
<script>
async_test(t => {
  assert_implements(document.startViewTransition, "Missing document.startViewTransition");
  let groupAnimationCount = 0;
  let oldAnimationCount = 0;
  let newAnimationCount = 0;
  let wrapperAnimationCount = 0;

  document.documentElement.addEventListener("animationstart", (e) => {
    let pseudo = e.pseudoElement;
    if (pseudo == "::view-transition-group(shared)") {
      groupAnimationCount++;
    } else if (pseudo == "::view-transition-new(shared)") {
      newAnimationCount++;
    } else if (pseudo == "::view-transition-old(shared)") {
      oldAnimationCount++;
    } else if (pseudo = "::view-transition-image-pair(shared)") {
      wrapperAnimationCount++;
    }

    let total =
      groupAnimationCount + oldAnimationCount + newAnimationCount + wrapperAnimationCount;
    // Old/new images have 2 animations : opacity and mix-blend-mode.
    if (total == 6) {
      t.step(() => assert_equals(groupAnimationCount, 1));
      t.step(() => assert_equals(wrapperAnimationCount, 1));
      t.step(() => assert_equals(oldAnimationCount, 2));
      t.step(() => assert_equals(newAnimationCount, 2));
      t.done();
    }
  });
  document.startViewTransition();
}, "verifies pseudo name includes a tag");

</script>

